1. Field of the Invention
The present invention relates to the patterning of crystalline films and more particularly to a method of altering the etch selectivity of crystalline films.
2. Discussion of Related Art
Semiconductor integrated circuits are fabricated from multiple layers of patterned thin films. Patterned single crystalline and polycrystalline thin films are used throughout manufacture of modern integrated circuits. For example, patterned semiconductor crystalline films, such as epitaxial silicon, gallium arsenide, and InSb are used to form semiconductor bodies or fins in nonplanar or tri-gate devices. Additionally, high dielectric constant metal oxide crystalline films are used to form gate dielectric layers in modern integrated circuits. Presently, crystalline films are patterned by first forming a mask with a desired pattern over a crystalline film. A wet etchant is then used to etch away the exposed portions of the crystalline film. Unfortunately, wet etchants undercut the mask resulting poor fidelity between the pattern in the mask and the resulting pattern in the crystalline film. Lack of fidelity between the patterning in the crystalline film and the mask limits the ability to further scale patterned dimensions of crystalline films. The ability to further scale the dimensions of crystalline films is essential in order to increase feature density in order to generate more powerful integrated circuits, such as microprocessors.